Surface condenser



Dec. 14, 1965 F. SCHULENBERG FIG.

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F. SCHULENBE RG SURFACE CONDENSER m m m Filed Dec. 27, 1962 Dec. 14,1965 m m E United States Patent 3,223,152 SURFACE CONDENSER FranzSchulenberg, Boehum, Germany, assignor to Gea- Luftkuhler-Gesellschaftrn.b.H., Bochum, Germany Filed Dec. 27, 1962, Ser. No. 250,729 11Claims. (Cl. 165-146) The present invention relates to surfacecondensers in general, and more particularly to a surface condenser forsteam and similar vaporous media which is preferably cooled byatmospheric air. Still more particularly, the invention relates to asurface condenser which is especially suited for condensing steam byexchange of heat with positively circulated directed currents of air.

This application is a continuation-in-part of my application Serial No.682,238, filed Sept. 5, 1957, now US. Patent No. 3,073,575.

It.is an important object of my invention to provide an apparatus whichis capable of condensing large quantities of vaporous media per unit oftime and which is constructed and assembled in such a way that, eventhough the medium to be condensed may be divided into two or morestreams, condensation of all such streams occurs at the same rate ofspeed and is sufficiently uniform to insure that each stream will yieldthe same amount of condensate if the streams contain identical volumesof a vaporous medium, or that each stream will yield proportionallyequal quantities of condensate if the streams contain differentquantities of a vaporous medium.

Another object of the invention is to provide an improved system oftubular conductors in which large quantities of steam or anothervaporous medium may be condensed in a simultaneous operation, whoseoperation is independent of temperatures prevailing in the surroundingatmosphere, which is equally useful for rapid condensation of a vaporousmedium in cold as well as in moderate or hot climates, and which may beassembled of a large number of identically configurated parts so that itmay be manufactured and assembled at reasonable cost.

A further object of my instant invention is to provide an air-cooledsurface condenser which may be constructed and assembled in such a waythat one or more of its sections may be shut off or reactivated toinsure that the capacity of the condenser corresponds to the volume ofthe vaporous medium which must be condensed per unit of time.

Still another object of the invention is to provide a surface condenserof the above outlined characteristics which may be manufactured of awide variety of readily available material and which may be constructedwith a view to eliminate or to reduce undesirable effects of so-calledboundary layers which normally hinder the exchange of heat between avaporous medium and the coolant.

The surface condenser of the present invention differentiates from theapparatus which is protected by the claims of my aforementioned patentin that its condenser units (ihereinafter also called condenserelements) comprise one or more rows of elongated tubular conductors ofdifferent heat exchanging capacity whereas the patented apparatusachieves a similar result by regulating the rate of flow (i.e., thetotal amounts) of a vaporous medium through the individual conductors.Of course, it is also within the purview of my invention to construct acondenser element in such a way that its conductors receive differentquantities of vaporous medium and are additionally constructed and/ orshaped in a manner to have different heat exchanging capacities.

With the above objects in view, the invention resides in the provisionof a surface condenser which comprises means for producing one or moredirected currents of coolant such as atmospheric air, at least onecondenser unit including (in its elementary form) two elongated tubularconductors arranged in such a Way that one thereof is located downstreamof the other as seen in the direction in which the coolant flows wherebythe one conductor is brushed by coolant which has been heated y andwhose cooling capacity has been reduced in response to exchange of heatwith the other conductor, a source of steam or another vaporous mediumcon nected with the intake end of each conductor, and means forreceiving condensate from the discharge end of each conductor.

In accordance with the present invention, the heat exchanging capacityof the one conductor is different from the heat exchanging capacity ofthe other conductor, and the arrangement is preferably such that theheat exchanging capacities of the conductors are selected with a view toinsure that the temperature of condensate discharged by both conductorsis at least approximately the same. Thus, the heat exchanging capacityof the one conductor is superior to the heat exchanging capacity of theother conductor. It can be said that the heat exchanging capacity ofconsecutive conductors, as seen in the direction of coolant flow,increases proportionally with the drop in cooling capacity of thecoolant so that the temperature of condensate at the discharge ends ofall of the conductors is at least approximately the same.

The heat exchanging capacities of the two conductors may differentiatefrom each other for a number of reasons, for example:

(a) Because the total area of heat exchanging surfaces on one of theconductors is different from the total area of heat exchanging surfaceson the other conductor;

(b) Because the thermal conductivity of the material of one of theconductors is different from the thermal conductivity of the material ofthe other conductor;

(c) Because the mass of one of the conductors is different from the massof the other conductor; and/or (d) Because one of the conductorscomprises means for reducing the effect of the boundary layer or becausethe boundary layer affecting means on one of the conductors is moreeffective than the boundary layer affect.- ing means on the otherconductor.

In addition, two or more of the above-outlined possibilities may beresorted to simultaneously, and it is equally possible to take advantageof one, two or more such possibilities in a surface condenser of thetype protected by my aforementioned patent wherein the tot-a1 amounts ofvaporous medium admitted to one of the conductors per unit of time aredifferent from the total amounts of vaporous medium admitted to theother conductor within the same period of time.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, W111be best understood from the following detailed description of certainspecific embodiments with reference to the accompanying drawings, inwhich:

FIG. 1 is a longitudinal vertical section through a complete condenserplant as seen in the direction of arrows from the line II of FIG. 2;

FIG. 2 is a partial top plan view of and a partial horizontal sectionthrough the condenser plant as seen in the direction of arrows from theline II-II of FIG. 1;

FIG. 3 is an enlarged transverse vertical section through the air-cooledcondensing part of the condenser plant as seen in the direction ofarrows from the line III-III of FIG. 2;

FIG. 4 is a front elevational view of a condenser element which formspart of the condenser plant shown in FIGS. 1 and 2;

FIG. is a section through the condenser element as seen in the directionof arrows from the line VV of FIG. 4;

FIG. 6 is a fragmentary partly end elevational and partly sectional viewof a modified condenser element which differentiates from the element ofFIGS. 4 and 5 in that its conductors comprise radial ribs of differentsurface areas, the section of FIG. 6 being taken along the line VIVI ofFIG. 7;

FIG. 7 is a transverse section as seen in the direction of arrows fromthe line VII-VII of FIG. 6;

FIG. 8 is a fragmentary partially end elevational and partiallysectional view of a further condenser element wherein the masses of theconductors are different;

FIG. 9 is a transverse section through an additional con- 1 denserelement wherein staggered groups of conductors comprise heat dissipatingelements of different materials and wherein the ribs of such heatdissipating elements are of different thicknesses;

FIG. 10 is a fragmentary partially end elevational and partiallysectional view of an additional condenser element wherein the groups ofconductors comprise heat dissipating elements consisting of differentmaterials but wherein the thickness of all of the ribs which form partof such heat dissipating elements is the same;

FIG. 11 is a similar fragmentary partly end elevational and partlysectional view of another condenser element wherein the groups ofconductors comprise heat dissipating elements and pipes consisting ofdifferent materials;

FIG. 12 is a transverse section through a further condenser elementwherein the rows of conductors are staggered with respect to each otherand wherein the heat dissipating elements in such staggered rows ofconductors consist of materials having different thermalcharacteristics;

FIG. 13 is a fragmentary front elevational view of another condenserelement which comprises three groups of o'val pipes and wherein certainheat dissipating elements comprise specially formed projections whichserve as a means for reducing the thickness of or for eliminating theboundary layer of insulating fluid which normally develops around theconductors;

FIG. 14 is a transverse section as seen in the direction of arrows fromthe line XIV-XIV of FIG. 13;

FIG. 15 is an end elevational view of the condenser element as seen inthe direction of arrows from the line XVXV of FIG. 14;

FIG. 16 is a transverse section through another condenser element whoseheat dissipating elements are formed with differently configurated anddifferently distributed projections; and

FIG. 17 is a side elevational view of another heat dissipating elementwhose rib is formed with projections at each of its sides.

Referring now in greater detail to the illustrated embodiments, andfirst to FIGS. 1 and 2, there is shown a condenser plant including asteam turbine 2 which drives an electric generator 3 or a like machineand which discharges spent steam through a conduit 1 leading to a pairof symmetrically arranged conduits 4 each of which branches off into apair of smaller-diameter conduits 4a for delivering steam to fourupright connecting conduits 5. The diameter of the conduits 1, 4, 4a areproportioned to each other in such a way that the speed at which steamflows therethrough is substantially the same, i.e., the combinedcrosssectional area of two conduits 4a equals the cross-sectional areaof the respective conduit 4, and so forth. As shown in FIG. 1, theconduits 4, 4a are laid below the ground, and FIG. 2 illustrates thatthe upright connecting conduits 5 are substantially equidistant fromeach other. The upper end of each conduit 5 is connected with twocoaxially arranged diverging steam distributing conduits 6, 6a, and eachof these steam distributing conduits feeds steam into two series ofcondenser elements or units 7, 7a. The diameters of the conduits 6, 6adiminish preferably 4 gradually in a direction away from the respectiveconnecting conduits 5 proportionally with the rate at which the conduits6, 6a feed steam to the respective series of condenser elements 7, 7a.

FIG. 3 shows that the associated series of condenser elements 7, 7a areinclined with respect to each other so as to resemble a roof structurewherein the respective steam distributing conduit 6 is disposed at alevel above and between the upper ends of the condenser elements. Thus,the condenser elements 7, 7a diverge downwardly and outwardly from theopposite sides of the respective conduit 6.

The lower ends of the series of condenser elements 7, 7a arerespectively connected with condensate collecting conduits 8, 8a whichare parallel with the steam distributing conduit-s 6, 6a. Thearrangement is preferably such that the condenser elements 7, 7a whichare connected to a common steam distributing conduit 6 or 6a form twosides of a substantially equilateral triangle (see particularly FIG. 3),and the space between each pair of condensate collecting conduits 8, 8aaccommodates one or more means for producing directed currents ofcoolant. Such means preferably assume the form of propeller blowers 9 ofcomparatively large diameter which are disposed in horizontal planes ata level somewhat below the level of the condensate collecting conduits8, 8a. FIG. 2 shows that three closely adjacent blOWers 9 may bearranged beneath each series of condenser elements 7, 7a and each bloweris preferably provide-d with a separate drive motor 10 which may beadjusted to drive the respective blower at a higher or lower speed.Furthermore, it is often desirable to provide each blower with blades 9awhose angle of incidence may be adjusted in any suitable way not formingpart of this invention so that each b'lower may be regulatedindependently of the other blowers to produce an air current of desiredvolume and/or speed. Condensate collected by conduits 8, 8a is conveyedunderground (arrows Z) by conduit means SD shown in FIGS. 1 and 2.

FIG. 3 illustrates that each series of condenser elements 7, 7a ismounted above an elongated suction chamber 11 open at all sides tocommunicate with large suction apertures 12 through which the blowers 9draw substantial quantities of atmospheric air, and such air isthereupon compelled to form an upwardly flowing directed current ofcool-ant and to pass through the gaps between the condenser elements 7,7a in order to exchange heat with steam which flows from the respectivedistributing conduit 6 or 61: toward the respective condensatecollecting conduits 8, 8a. Currents of air created by the blowers 9 areindicated in FIG. 3 by arrows X, whereas the arrows Y (FIGS. 1 and 2)indicate the flow of steam through the conduits 4 and toward thecondenser elements 7, 7a. Walls 12a which surround the condenserelements 7, 7a form a duct through which heated air flows into theatmosphere so that such heated air cannot return directly into thesuction chambers 11. In other words, air which has already passedthrough the condenser must be thoroughly mixed with cooler atmosphericair before it can be recirculated through the chambers 11.

It is not always necessary to arrange the condenser elements 7, 7a inmutually inclined double series or rows since such condenser elementsmay be disposed in horizontal planes or in planes which are inc-linedthrough more or less than 60 degrees with respect to the planes of theblowers 9. However, :it is normally desirable that the surface condensercomprise several condenser elements 7 and/or 7a which are connected inparallel insofar as the flow of vaporous medium is concerned, and whichare cooled by exchanging heat with one or more directed currents of airor another coolant. As a rule, the currents of coolant are produced anddirected to flow in a predetermined path artificially by means ofblowers or the like. Furthermore, and as will be explained in connectionwith FIGS. 4 and 5, each condenser element 7 or 7a should comprise atleast two steam conveying conduits or pipes which are spaced from eachother as seen in the direction of air flow and which are connected inparallel so that each thereof may receive a stream of steam or anothervaporous medium from a common source.

Referring now to FIGS. 4 and 5, the-re is shown a condenser element orunit 7 comprising a distributor or header 18 of large cross-sectionalarea which is connected with the steam distributing conduit 6 by ahollow connector 20 so that steam admitted into the header 18 (arrows Y)may be divided into several rows of smaller streams each including threestreams U U U which are caused to enter through the intake ends of threespaced but aligned parallel conduits or pipes 13, 14, 15 and to flow ina direction toward a condensate-collecting header 19 which communicateswith one or more hollow connectors 21 serving as a means for admittingcondensate into the collecting conduit 8. The connector 20 preferablyextends substantially along the entire length of the header 18. Theconnector or connectors 21 may be replaced by a tubular member whichresembles the connector 20. It will be noted that the axes of the pipes13-15 shown in FIG. 5 are perpendicular to the direction of flow ofcooling air current (arrows X), and that these pipes are equally spacedfrom each other in the direct-ion indicated by such arrows so that steamadmitted into the intake end of the median pipe 14 exchanges heat withair which has been preheated by exchange of heat with steam admittedinto the intake end of the front pipe 13, and that steam admitted intothe intake end of the rear pipe 15 exchanges heat with air which hasbeen heated first -by exchanging heat with steam passing through thefront pipe 13 and thereupon with steam passing through the median pipe14. In accordance with my invention, the condenser element 7 isconstructed and assembled in such a way that the temperature of all ofthe fluid streams (be it condensate or gas) which are discharged throughthe discharge ends of the pipes and enter the header 19 is at leastnearly the same irrespective of the fact that the three streams werecaused to exchange heat with air currents whose temperature rises asthey pass from the front pipe 13 to the median pipe 14 and finallytoward and beyond the rear pipe 15.

FIG. 4 shows that the condenser element 7 comprises eight sets of pipes13-15 (only the front pipes 13 are shown) and that the axes of all pipes13, 14 or 15 are located in common planes which are perpendicular to thedirection of air flow. In other words, steam admitted to the header 18by the connector 20 is divided into twentyfour smaller streams each ofwhich passes through a separate pipe, and the condensate which thestreams of steam yield in the respective pipes is thereupon dischargedinto the second header 19 to be conveyed through the connector orconnectors 21 and into the collecting conduit 8. The header 19communicates with a further hollow connector 22 leading into an exhaustconduit 23 which leads to an air evacuating device 23a shown in FIGS. 1and 2. This air evacuating device may assume the form of a so-calledsteam ejector pump and serves as a means for creating partial vacuum inthe pipes 13, 14 and 15 and for thereby causing steam or anothervaporous medium to flow through the condenser element 7. In addition,the device 23a withdraws air which remains in the header 19 uponevacuation of condensate into the collecting conduit 8.

It goes without saying that each condenser element 7 or 7a may beequipped with a separate air evacuating device 23a or that a single airevacuating device may be connected with two, more or all conductors, thelatter modification having been shown in FIGS. 1 and 2. Of course, it isequally possible to omit the conduits 23 and the connectors 22 and toconnect the air evacuating device or devices 23a directly to thecondensate collecting conduits 8, 8a. The air evacuating device 23a ofFIGS.

6 1 and 2 is assumed to maintain the internal spaces of the condenserelements 7, 7a at a pressure of about 0.05 atmosphere absolute pressure.

As clearly shown in FIGS. 1 to 5, the header 18 and the steam conduitryconnected thereto together constitute a source of vaporous medium whosetemperature is higher than the temperature of coolant. This source isconnected to all of the pipes 13 to 15 so that the temperature ofstreams of vaporous medium entering these pipes is at least nearly thesame.

In accordance with my invention, the condenser element or unit 7comprises three difierent types of heat dissipating or heat transmittingelements 24, 25, 26 which are respectively mounted on and surround thepipes 13, 14 and 15. Each heat dissipating element comprises a sleeveand a circular or polygonal washer-like fin or rib 27. The diameters andthe areas of all fins 27 are the same whereas the sleeves 28b of theheat dissipating elements 25 are shorter than the sleeves 28a of theheat dissipating elements 24 but longer than the sleeves 280 of the heatdissipating elements 26. In other words, the combined area of heatexchanging external surfaces of all heat dissipating elements 25 on anygiven median pipe 14 is greater than the combined area of heatexchanging external surfaces of all heat dissipating elements 24 on anygiven front pipe 13 but smaller than the combined area of heatexchanging external surfaces of all heat dissipating elements 26 on anygiven rear pipe 15. Consequently, the heat exchanging capacity of eachsteam conductor 14, 25 is less than the heat exchanging capacity of eachsteam conductor 15, 26 but greater than the heat exchanging capacity ofeach steam conductor 13, 26. The expression steam conductor has beenchosen to denote a pipe 13, 14 or 15 and all such heat dissipatingelements (24, 25 or 26) which are mounted on the respective pipe. Ofcourse, each such steam conductor may be modified by omitting the pipe13, 14 or 15 and by assembling the sleeves 28a, 28b or 280 in such a waythat they form a fiuidtight tubular body. As clearly shown in FIG. 5,the sleeves 28a of coaxial heat dissipating elements 24 abut against thefins 27 of the adjacent heat dissipating elements 24 so that the sleeves28a actually form a second pipe which surrounds the respective front pip13. The mounting of heat dissipating elements 25, 26 on the respectivemedian and rear pipes 14, 15 is analogous. FIG. 5 illustrates that,owing to such mounting of the heat dissipating elements, the distance Tbetween a pair of adjacent ribs 27 on a median pipe 14 exceeds thedistance T between a pair of adjacent ribs 27 on a rear pipe 15 but isless than the distance T between a pair of adjacent ribs 27 on a frontpipe 13. In other words, the heat exchanging capacities of the threegroups of steam conductors 13, 24; 14, 25; 15, 26 are different owing tothe fact that each conductor 14, 25 comprises a larger number of ribs 27than a conductor 13, 24 but a lesser number of ribs 27 than a conductor15, 26. The heat exchanging capacities of the three groups of conductorsare correlated in such a way that they are inversely proportional to thetemperature of the air currents (arrows X), such temperature beingmeasured along the exterior and in immediate proximity of the respectivesteam conductor. Thus, since the temperature of the air currents islowest at the time such currents exchange heat with the steam conductors13, 24, the heat exchanging capacity of these steam conductors is lessthan the heat exchanging capacity of the conductors 14, 25 which latterare contacted by and exchange heat with the air currents only at thetime such currents were heated by exchanging heat with the steamconductors 13, 24. The same applies to the steam conductors 15, 26 whichexchange heat with the air currents after the latter were heated to anelevated temperature by previous exchange of heat first with one or moreconductors 13, 24 and thereupon with one or more conductors 14, 25. Itis not difficult to select the heat exchanging capacities of the threegroups of steam conductors in such a way that the temperature ofcondensate discharged by the median pipes 14 is the same as orapproximates the temperature of condensate which is discharged from thepipes 13 or 15.

The diameters of the/pipes 13 are identical with the diameters of thepipes 14 and 15, and all pipes are of identical length and of identicalcross-sectional configuration. In other words, the so-called hydraulicdiameters of all pipes are the same whereby each pipe may be assumed toconduct identical quantities of steam per unit of time. In actualoperation, the situation is normally somewhat different because, even ifthe diameters, the lengths and the cross-sections of all pipes are thesame, the front pipes 13 will convey greater quantities of steam thanthe pipes 14 and 15. However, the difference is rather negligible sothat one can say without exaggeration that the volume of steam conveyedthrough a front pipe 13 corresponds substantially to the volume of steampassing through a pipe 14 or 15, i.e. the differences are minor and, asa rule, require no special attention at the time one calculates thecapacity of a condenser element.

The thickness of each rib or fin 27 and the wall thickness of eachsleeve 28a, 28b or 28c is also the same. In addition, the finish ofexternal surfaces on each of the heat dissipating elements 24, 25, 26 isalso the same and all such elements are made of identical material,e.g., steel, aluminum or copper. In other words, the heat dissipatingelements 24 differ from the heat dissipating elements 25 or 26 solely inthe length of their sleeves whereas all remaining characteristics anddimensions of the heat dissipating elements 24-26 are the same. Theratio T :T :T is inversely proportional with the difference between thetemperature of air currents brushing the conductors 13, 24; 14, 25; 15,26 and the temperature of steam admitted to the pipes 13, 14, 15. Thus,since the difference between the temperature of air brushing the heatdissipating elements 26 and the temperature of steam passing through therear pipes 15 is less than the difference between the temperature of airbrushing the elements 25 and the temperature of steam passing throughthe median pipes 14, the heat exchanging capacity of a condutcor 15, 26is greater than the heat exchanging capacity of a conductor 14, 25. Thesame applies to the heat exchanging capacities of the conductors 14, 25and 13, 24.

In certain presently utilized surface condensers, the steam conductorsin all groups are arranged in a manner similar to that shown in FIGS. 4and 5 and each pipe receives the same quantity of steam. However, sincethe overall area of heat exchanging surfaces on all steam conductors isthe same, condensation in the first group of conductors which come intocontact with cooler air is more rapid than in the conductors which arelocated downstream of the first group of conductors. In other words,condensation in various conductors of the same condenser element or unitvaries considerably so that all of the steam conveyed through the firstgroup of conductors may be condensed at a point spaced from thecondensate collecting conduit whereas steam passing through the othergroup or groups of conductors will be condensed immediately ahead of thecondensate collecting conduit or it can happen that the condensation ofsteam flowing through certain conductors is only partial, i.e., thatsome steam may enter the condensate collecting conduit. It is obviousthat the efficiency of such conventional condensate elements is ratherlow since the conductors which come into contact with cold air are toolong whereas the length of certain other conductors is insufficient toinsure full condensation of all of the steam passing therethrough. If aconductor is too long, the last portion thereof undergoes unnecessaryundercooling. Such undercooling of steam conductors and of condensate isvery undesirable in cold climates, particularly in heavy frost, becausethe condensate may be cooled below freezing point and the correspondingconductor or conductors are choked or sealed by ice plugs. Once suchchoking occurs, the next group of conductors is also cooled to a lowertemperature which may be sufficiently low to cause freezing ofcondensate, i.e., even in the second group the boundary between thecondensation range and the undercooling range moves further away fromthe condensate collecting conduit so that ice plugs developing in suchnext group of conductors prevent outflow of condensate and permit verycool air to undesirably reduce the temperature of condensate in thethird, fourth etc. group, depending upon the number of group-wisearranged conductors in the condenser element. Such formation of iceplugs in one, two, three or even more groups of steam conductors isobservable in conventional surface condensers at temperatures of about20 C. It can happen that the surface condenser freezes up entirely orthat its capacity is reduced to a very great extent.

The condenser element or unit 7 of FIGS. 4 and 5 avoids such drawbacksof just described conventional condenser elements merely by having theindividual steam conductors arranged in such a way that the heatexchanging capacity of the conductors varies in the direction of coolantflow, i.e., the heat exchanging capacity of conductors which are brushedby coolest air is less than the heat exchanging capacity of conductorswhich are located downstream thereof, as seen in the direction of airflow, and so on, so that the heat exchanging capacity of the conductorspreferably increases at the same rate at which the temperature of theair stream increases to insure that the formation of condensate iscompleted at or in immediate proximity of the condensate collectingconduit 8 or, better to say, in close proximity of the header 19 so thatundercooling of condensate is very unlikely. If the temperature ofatmospheric air varies considerably, the blowers 9 may be adjusted (bychanging their rotational speed, i.e., by adjusting the motors 10, and/or by changing the angle of incidence of the blades 9a) so that thecirculation of very cool air is less pronounced than the circulation ofair on warmer days. Consequently, subcooling of condensate and theformation of ice plugs in the conductors of my improved condenserelement 7 is very unlikely 0r plainly impossible, and the condensationtakes place by far better utilization of the available heatexchangingsurfaces which is of advantage not only at low temperatures but also inwarmer climates. Furthermore, the likelihood that some steam(particularly in conductors which are brushed by comparatively warm aircurrents) would enter the condensate collecting conduits is very remoteso that the device 23a will not extract any steam from the system.

It will be readily understood that the condenser elements or units 7aare identical with the condenser element 7 of FIGS. 4 and 5 exceptingthat they discharge the condensate into collecting conduits 8a. By thesame token, the condenser element 7 of FIGS. 4 and 5 is identical withcertain other condenser elements 7 which are shown in FIG. 2 asreceiving steam from conduits 6a. In other words, all condenser elementsof the surface condenser shown in FIGS. 1 and 2 may be of identicalconstruction. Of course, such identity of all condenser elements 7, 7ais not essential for proper operation of the surface condenser but ispreferred because a so constructed apparatus may be manufactured andassembled at a cost which is less than the cost of a surface condenserwherein the condenser elements in one group would be different from thecondenser elements in the other groups or wherein each group wouldcontain two or more differently constructed or dimensioned condenserelements.

The condenser element or unit of FIGS. 4 and 5 may be modified in anumber of ways without departing from the spirit of my invention. In itssimplest form, the condenser element may comprise only two steamconductors, for example, a conductor 13, 24 and a conductor 14, 25 or15, 26. Furthermore, the condenser element may comprise one or more rowsof four, five or even more steam conductors, as viewed in the directionof arrows X in FIG. 5, even though it is normally impractical to formthe condenser element with rows of more than five conductors. As a rule,and insofar as I am advised at this time, the condenser elementpreferably comprises one or more rows of three or four steam conductors.Of course, the number of rows of such conductors (eight such rows havingbeen shown in FIG. 4) may be increased or reduced, depending on thedesired capacity of the condenser element. I have found that, if thenumber of steam conductors in a row exceeds five, i.e., if the row ofthree conductors shown in FIG. 5 were replaced by a row of six, seven ormore conductors, the sixth, seventh, etc. conductors come in contactwith air currents which were preheated by exchange of heat with thefirst five conductors of the same row to such an extent that there isvery little difference between the temperature of such additionalconductors and the temperature of air, i.e., the cooling effect of airwhich was preheated five or more times is frequently negligible.

For example, if the difference between the temperature of steam enteringa front pipe 13 and the mean temperature of air brushing the heatdissipating elements 24 is 40 C., if the difference between thetemperature of steam entering a median pipe 14 and the mean temperatureof air brushing the elements 25 is 30 C., and if the difference betweenthe temperature of steam entering a rear pipe 15 and the meantemperature of air brushing the elements 26 is 23 C., the ratio of heatexchanging surfaces and capacities of conductors 13, 24; 14, 25; 15, 26should be 1/40zl/ 30:1/23. In other words, the ratio of the temperatureof steam in the header 18 to the mean temperature of air brushing thethree groups of steam conductors should be inversely proportional withthe ratio of the heat exchanging surfaces and heat exchanging capacitiesof such conductors. Such construction of steam conductors insures thatthe temperature of all streams of condensate entering the header 19 issubstantially the same.

FIGS. 6 and 7 illustrate a modified condenser element or unit 107 whichcomprises six rows of steam conductors and wherein each such rowcomprises three steam conductors of different heat exchangingcapacities. The pipes 113, 114, 115 of all six rows of steam conductorsare connected directly to a steam admitting header 118. Each front pipe113 is surrounded by a series of coaxial heat dissipating or heattransmitting elements 124 and each such element comprises a sleeve 128and a substantially square rib or fin 127a. The heat dissipating or heattransmitting elements 125 on the median pipes 114 comprise sleeves 128and rectangular ribs or fins 1271? whose area is greater than the areaof the ribs 127a. Finally, the heat dissipating or heat transmittingelements 126 on the rear pipes 115 comprise sleeves 128 and ribs or fins1270 whose area is greater than the area of the ribs 127b. Thus, theheat exchanging surface of each steam conductor 114, 125 is greater thanthe heat exchanging surface of a conductor 113, 124 but smaller thanthat of a conductor 115, 126. The axial length of all sleeves 128 is thesame so that the difference in the heat exchanging capacities of thethree groups of steam conductors is obtained by providing the elements125 with ribs 127:) whose heat exchanging surfaces are greater than theheat exchanging surfaces of the ribs 127a but smaller than the heatexchanging surfaces of the ribs 1270. The diameters and the lengths ofall pipes 113, 114, 115 are the same and the material of each steamconductor 114, 125 is the same as that of a steam conductor 113, 124 or115, 126. The manner in which the header 118 receives steam from adistributing conduit and the manner in which the pipes 113, 114, 115discharge condensate into a collecting header and thence into acollecting conduit is the same as described in connection with FIGS. 1to 5. Steam admitted into the header 118 in the direction indicated bythe arrow Y is divided into eighteen smaller streams, there being sixstreams flowing through the group of front pipes 113 (arrow U sixstreams flowing through the group of median pipes 114 (arrow U and sixstreams flowing through the group of rear pipes (arrow U The aircurrents flow in the direction indicated by arrows X.

It will be noted that, in contrast to the construction of FIGS. 4 and 5,the three groups of steam conductors in the condenser element or unit107 have different heat exchanging surfaces not because their heatdissipating elements are formed with sleeves of different length butrather because they comprise ribs or fins of different areas. The endresult is the same as in the condenser element 7, i.e., condensateflowing from the median pipes 114 has the same or nearly the sametemperature as the condensate flowing from the pipes 113 or 115. Thedistance T between adjacent pairs of ribs 127a, 127b or 1270 is alwaysthe same, i.e., all sleeves 128 are of identical axial length. The wallthickness of all sleeves 128 is the same, and the same applies for thethicknesses of the ribs 127a, 127b, 1270.

It will be understood that similar results can be obtained if some orall of the ribs 127a, 127b, 1270 are replaced by ribs of circular, oval,triangular, square, hexagonal or other shape. In other words, theillustration of square ribs 127a and of rectangular ribs 127b, 1270should not be construed in a limitative sense because similar resultscan be obtained with otherwise configurated ribs so long as such ribsinsure that the heat exchanging surfaces of the corresponding heatdissipating elements are selected in such a way that the temperature ofcondensate discharged from all steam conductors is substantially thesame.

It is equally possible to reduce the number of steam conductors in eachgroup or to form the condenser element or unit 107 with rows whichcomprise two, four or more conductors.

The axes of all pipes 113, 114 or 115 are disposed in a common plane andare substantially perpendicular to the direction of air flow.

The condenser element or unit 207 of FIG. 8 comprises one or more rowsof pipes 213, 214, 215 whose intake ends are connected to a header 218so as to receive streams U U U of steam or another vaporous medium whichenters the distributor 218 in a direction indicated by the arrow Y. Inthis embodiment of my invention, the ribs 227a, 227b, 2270 whichrespectively form part of three different heat dissipating or heattransmitting elements 224, 225, 226 are of identical outlines andconsist of identical material (e.g., steel, aluminum or copper);however, the thickness D of each rib 227b exceeds the thickness D of arib 227a but is less than the thickness D of a rib 2270. The sameapplies for the sleeves 228a, 228b, 2280 which consist of the samematerial and are of identical axial lengths; however, the wall thicknessof each sleeve 22812 is greater than the wall thickness of a sleeve 228abut less than the wall thickness of a sleeve 2280. Consequently, theheat exchanging capacity of the conductor 214, 225 is greater than theheat exchanging capacity of the conductor 213, 224 but is less than thatof the conductor 215, 226. The wall thicknesses of the heat dissipatingelements 224, 225, 226 are again selected in such a way that thetemperature of condensate discharged from the pipes 213, 214, 215 is atleast approximately the same. The pipes 213-215 consist of the samematerial and their axial lengths and diameters are identical.

Of course, after looking at FIG. 8, one could say that the sleeves 22812are shorter than the sleeves 228a but longer than the sleeves 2280.However, if one considers that the innermost portion of each rib 227a,227b, 2270 forms part of the respective sleeve, then the sleeves may besaid to be of identical lengths.

It can also be said that the heat exchanging surface of the conductor214, 225 is identical with the heat exchanging surface of the conductors213, 224 or 215, 226. Thus, the feature that the heat exchangingcapacity of the conductor 214, 225 is greater than that of the conductor213, 224 but less than that of the conductor 215, 226 is due to the factthat the mass of the conductor 214, 225 is greater than that of theconductor 213, 224 but less than the mass of the conductor 215, 226. Inother words, instead of utilizing steam conductors with heat exchangingsurfaces of different areas, one can achieve the same result by usingsteam conductors with different masses or volumes, the expressionvolumes being intended in this instance to denote the total mass of apipe and of all heat dissipating elements which are mounted thereon.

The distance between the axis of the median pipe 214 on the one hand andthe axes of the pipes 213, 215 on the other hand is the same, i.e., thepipes in the row which is illustrated in FIG. 8 are equidistant fromeach other. Of course, the condenser element 207 may comprise two ormore rows of pipes 213-215 so that two or more pipes 213 form a frontgroup of aligned pipes whose heat dissipating elements 224 are first tocome into contact with cool air flowing in the direction indicated byarrows X, that two or more pipes 214 form a median group of alignedpipes which is located downstream of the front group, and that two ormore pipes 215 form a rear group of pipes which is located downstream ofthe pipes 214, as viewed in'the direction of arrows X. Furthermore, thecondenser element 207 may be modified by omitting one of the pipes shownin FIG. 8 or by adding one or more pipes in each row so that thiscondenser element may comprise say two, three or more rows of pipeswherein the number of pipes normally does not exceed five for thereasons explained hereinbefore. In this description, different steamconductors are being said to form rows which (in the embodiments ofFIGS. 1 to 8) are disposed in comm-on planes, and two or more identicalsteam conductors (see FIG. 4 or 7) are said to be arranged in groupswhich, in the embodiments of FIGS. 1 to 8, are also arranged in commonplanes, such planes being preferably perpendicular to the direction ofair flow.

The condenser element 207 is constructed with a view to take advantageof the fact that the transfer of heat from the interior of athick-walled body to the surrounding atmosphere is greater than thetransfer of heat from the interior of a thin-walled body. The thickerthe ribs 22711-2270 and/or the walls of the sleeves 228a- 2280, thebetter will be the transfer of heat from a vaporous medium surrounded bysuch heat dissipating elements to the current of air which brushes theexterior of the heat dissipating elements. It will be readily understoodthat, at least in some instances, it is sufficient if only the wallthickness of the sleeves 228a2280 or of the ribs 227a-227c is different.When applied in the condenser element 207 of FIG. 8, this would meanthat one could reduce the thickness of the ribs 2270 by simultaneouslyincreasing the wall thickness of the sleeves 2280 so that the thicknessof the ribs 2270 would approximate or be even less than that of the ribs227]; or 227a. All that counts is that the thicknesses of the ribs and/or the wall thicknesses of the sleeves be selected with a view to insurethat the temperature of condensate which is discharged from the medianpipe 214 is substantially the same as or identical with the temperatureof condensate which is discharged from the pipe 213 or 215.

Referring to FIG. 9, there is shown a condenser element or unit 307which comprises three groups of pipes 313, 314, 315 and each such groupcomprises seven pipes. In contrast to the construction of the condenserelements 7, 107 and 297, the group of front pipes 313 is not arranged ina common plane but rather in Zig-zag formation. Thus, and counting fromthe left-hand side of FIG. 9, all oddly numbered pipes 313 are disposedin a first plane which is preferably perpendicular to the direction ofair flow (arrows X), and all evenly numbered pipes 313 are disposed in asecond plane which is parallel with and is located downstream of thefirst place. The median pipes 314 and the rear pipes 315 are arranged inidentical fashion. It will be noted that each front pipe 313 is alignedwith a median pipe 314 and with a rear pipe 315, as viewed in thedirection of arrows X, so that the pipes form seven rows of pipes withthe median pipes 314 located upstream of the respective rear pipes 315but downstream of the respective front pipes 313, as viewed in thedirection of air flow.

Each front pipe 313 is surrounded by a series of heat dissipating orheat transmitting elements 324 having sleeves 328a of identical axiallengths and rectangular ribs 327a, such pipes and the heat dissipatingelements 324 mounted thereon forming a group of seven steam conductorswhich may receive steam and which may discharge condensate in the sameway as described in connection with FIGS. 4 and 5. The heat dissipatingor heat transmitting elements 325 on the median pipes 314 comprisesleeves 32819 and rectangular ribs 327b whose configuration is the sameas but whose thickness exceeds the thickness of the ribs 327a. Thethickness of the ribs 3270 which together with the sleeves 3280constitute heat dissipating or heat transmitting elements 326 for therear ipes 315 is greater than the thickness of the ribs 327b.

Furthermore, the material of the heat dissipating elements 325 is abetter thermal conductor than the material of the heat dissipatingelements 324, and the material of the heat dissipating elements 326 is abetter thermal conductor than the material of the heat dissipatingelements 325. For example, the heat dissipating elements 324 may be madeof steel, the heat dissipating elements 325 may consist of aluminum, andthe heat dissipating elements 326 may consist of copper. Thus, theadvantage that the temperature of condensate discharged from all of thepipes 313, 314, 315 is substantially the same is due to the combinationof two features, namely, that the thickness of the ribs 32711 is greaterthan the thickness of the ribs 327a but less than the thickness of theribs 3270, and also that the material of the ribs 327b (and preferablyof the entire elements 325) is a better thermal conductor than thematerial of the ribs 327a but inferior to the material of the ribs 3270.Otherwise, the dimensioning of all of the steam conductors 313, 324;314, 325; 315, 326 is the same and the pipes 313-315 may consist ofidentical material. The feature that the thermal conductivity of thematerial of the ribs 327a is less than the thermal conductivity of thematerial of the ribs 327b and that the thermal conductivity of thematerial of the ribs 327]) is less than the thermal conductivity of thematerial of the ribs 3270 is indicated in FIG. 9 on one of the ribs 327aby closely adjacent inclined lines 327a, on one of the ribs 32717 by aset of more widely spaced inclined line 32712, and on one of the ribs3270 by a set of widely spaced inclined lines 3270'.

For example, the ratio of the thickness of the ribs 327a, 327b, 327a maybut need not always be 3:425. Of course, and as will be explainedhereinafter, it is equally possible to utilize ribs of identicalthicknesses and to rely solely on different thermal conductivity ofmaterials of which the ribs, the entire heat dissipating elements and/or the pipes are made.

In the condenser element or unit 407 of FIG. 10, all of the heatdissipating or heat transmitting elements 424, 425, 426 and all of thepipes 413, 414, 415 are of identical configuration and of identicaldimensions. However, the material of the heat dissipating elements 425is a better conductor of heat than the material of the heat dissipatingelements 424. Also, the material of the heat dissipating elements 426 isthe best conductor of heat. For example, the heat dissipating elements424 may be made of steel, the heat dissipating elements 425 may consistof aluminum, and the heat dissipating elements 426 may consist ofcopper. The hatching of the heat dissipating elements 425 is denser thanthe hatching of the heat dissipating elements 426 but less dense thanthe hatching of the heat dissipating elements 424 to indicate visuallythat the thermal conductivity of the steam conductor 414, 425 issuperior to that of the conductor 413, 424 but inferior to that of theconductor 415, 426. The pipes 413415 consist of identical material andreceive streams of steam (arrows U U U from a common header 418. Theribs 427a427c may be of circular, oval or polygonal shape and areintegral with the respective sleeves 428a, 428b, 428a.

-A further embodiment of my invention which is so obvious that itrequires no illustration comprises one or more rows of pipes whichconsist of different materials and heat dissipating elements ofidentical material. Another readily conceivable modification maycomprise one or more rows of pipes made of materials having differentheat conductivities and surrounded by heat dissipating elements ofidentical material but of different wall thicknesses so that the heatexchanging capacity of the front conductor or conductors will be lessthan the heat exchanging capacity of the conductor or conductors locateddownstream thereof.

In the condenser element or unit 507 of FIG. 11, the front pipe 513 andthe heat dissipating or heat transmitting elements 524 consist ofmetallic material which is a comparatively poor conductor of heat whencompared to the thermal conductivity of the material of the median pipe514 and of the heat dissipating or heat transmitting elements 525, andwhich is an even poorer conductor of heat when compared with the thermalconductivity of the material of the pipe 515 and of the heat dissipatingor heat transmitting elements 526. For example, the steam conductors513, 524; 514, 525; 515, 526 may respectively consist of steel, aluminumand copper. Otherwise, the dimensions and all other characteristicfeatures of all of the pipes 513-515 are the same, and this also appliesfor the heat dissipating elements 524-526. The pipes 513- 515 areequidistant from each other, and it will be readily understood that thecondenser element 507 may comprise two or more rows of steam conductorswhich may be arranged in coplanar groups or in zig-Zag fashion asillustrated in FIG. 9, and the pipes 513515 receive streams of steamfrom a common header 518.

The condenser element or unit 607 of FIG. 12 comprises three groups ofpipes 613, 614, 615 which may consist of steel. The front and the reargroups (as seen in the direction of arrows X) respectively comprise sixcoplanar pipes 613, 615, whereas the median group comprises merely fivecoplanar pipes 614 which are staggered with respect to the pipes 613,615. The thermal conductivity of the heat dissipating or heattransmitting elements 624 on the front pipes 613 of the uppermost groupof steam conductors, as viewed in FIG. 12, is poorer than the thermalconductivity of heat dissipating or heat transmitting elements 625 onthe median pipes 614, and the thermal conductivity of the heatdissipating or heat transmitting elements 626 on the rear pipes 615 issuperior to that of the heat dissipating elements 625. For example, theheat dissipating elements 624, 625, 626 may respectively consist ofsteel, aluminum and copper. Of course, many different variations arepossible in the selection of materials for the heat dissipating elements624 626, and this also applies for the parts shown in FIGS. 9 to 11;thus, it is possible to utilize various alloys of the aforementionedmetals and of certain other metals as long as such alloys exhibit thedesirable heat conducting characteristics.

The parts identified by numerals 641, 642 are bafiies which compel thecurrents of air flowing in the direction of arrows X to impinge againstthe heat dissipating elements 624-626 in this order, i.e., the currentsof air are compelled to pass through the gaps 643 between the heatdissipating elements 624, thereupon through the gaps 644 between theheat dissipating elements 625, and finally through the gaps 645 betweenthe rearmost heat dissipating elements 626 before such currents can mixwith cooler atmosphericair. It will be noted that the configuration ofall of the heat dissipating elements 624- 626 is the same and that thewidth of the gaps 643645 is also the same throughout the entirecondenser element 607. In this embodiment of my invention, each frontconductor 613, 624 is aligned with and forms a row with a rear conductor615, 626 but is out of alignment with a median conductor 614, 625. Animportant advantage of such construction is that air currents passingthrough the gaps 643 are compelled to impinge squarely against the heatdissipating elements 625, and that air currents passing through the gaps644 are also compelled to impinge squarely against the heat dissipatingelements 626, i.e., contact between the air currents and the steamconductors is superior to that in the previously described condenserelements.

It goes without saying that the number of pipes in each of the threegroups may be increased or reduced, and that one or more additionalgroups of staggered steam conductors may be added if necessary.

Referring to FIGS. 13, 14 and 15, there is shown a further condenserelement or unit 707 which comprises nine parallel pipes of oval orelliptical cross section. The length, cross-sectional configuration andthe material of all nine pipes is the same. As illustrated in FIG. 14,the condenser element 707 includes three front pipes 713 which aresurrounded by heat dissipating or heat transmitting elements 724 each ofwhich comprises a sleeve 728a and a smooth-surfaced rectangular rib orfin 727a; three pipes 714 surrounded by heat dissipating or heattransmitting elements 725 each of which includes a rib 727b and a sleeve72%; and three pipes 715 surrounded by heat dissipating or heattransmitting elements 726 each of which comprises a sleeve 728s and arib 7270. The front pipes 713 are coplanar and form a group whose planeis perpendicular to the direction of air flow (arrows X), and each frontpipe 713 forms with a medium pipe 714 and with a rear pipe 715 a rowcoplanar pipes which are disposed in planes parallel with the directionof air flow. It is assumed that the heat dissipating elements 724726 areof identical configuration, of identical dimensions and of identicalmaterial, e.g., steel, aluminum, copper or an alloy of such metals. Thespacing between all of the steam conductors 713, 724; 714, 725; 715, 726is the same, and it is assumed that the pipes 713-715 receive a vaporousmedium from a common header 718, see the arrows U U and U The longeraxis of the elliptical outline of each pipe is parallel with thedirection of air flow.

In order to insure that the temperature of condensate which isdischarged from the front pipes 713 is at least substantially the sameas the temperature of condensate discharged from a pipe 714 or 715, oneside of each of the ribs 727b and 7270 is respectively provided withsuitable projections or lugs 750B, 7500 which serve as a means forreducing the thickness of or for eliminating the socalled boundary layerof air or another coolant which is formed around the heat dissipatingelements and which hinders the exchange of heat between the steamflowing through the pipes 713-715 and the surrounding air currents. Inthe embodiment of FIGS. 13 to 15, the projections 750B, 750C are formedby stamping or by a similar method in that each such projection assumesthe form of a rectangular lug which is bent from the general plane ofthe respective rib and into a plane which is substantially perpendicularto the plane of the respective rib. As shown, the ribs 727a are withoutsuch projections so that the effect of boundary layer is felt morestrongly on the heat dissipating elements 724 which are first to comeinto contact with currents of cooling air. The ribs 727b are formed withfour symmetrically arranged projections 750B which are disposed in orclose to the four corners of these ribs and are located in planesparallel with the direction of air flow so that such projections 750Btend toweaken the effect of the boundary layer and permit betterexchange of heat between the steam flowing through the median pipes 714and the currents of air which was preheated by contact with the heatdissipating elements 724. Each rib 7270 is formed with six projections7500 which are similar to or identical with the projections 750B andwhich are. capable of weakening the effect of the boundary layersurrounding the heat dissipating elements 726 to such an extent that theexchange of heat between the steam flowing through the rear pipes 715and atmospheric air which was preheated by contact with the heatdissipating elements 724, 725 is better than the exchange of heatbetween the air current and the steam conductors 713, 724 or 714, 725.The projections 750C on each of the ribs 727c are arranged in two rowseach comprising three such projections, and it will be noted that all ofthe projections 750B, 7500 are disposed in such a way that they are notconcealed by the pipes 713-715, as viewed in the direction of air flow.The feature that the influence of the boundary layer may be weakened orthat such boundary layer may be eliminated is utilized in the condenserelement 707 to insure that the exchange of heat between the conductorsand the air currents improves at the same rate at which the temperatureof the air currents rises to thereby insure that the ultimate effect ofthis condenser element will be the same as or similar to that of thepreviously described condenser elements. Of course, it goes withoutsaying that the number of pipes 713-715 may be increased or reducedtogether with the number of heat dissipating elements, and that theprojections 750B, 750C may be arranged in a number of other ways. Forexample, and as shown in FIG. 16 which illustrates a very simplecondenser element or unit 807 having a single roW of steam conductors813, 824; 814, 825; 815, 826, each heat dissipating or heat transmittingelement may be provided with means for reducing the effect of or foreliminating the boundary layer. In this embodiment of my invention, eachof the ribs 827 which together with the sleeves 828 constitute the heatdissipating elements 824 is provided with a single projection 850A whichis parallel with the direction of air flow (arrow X) and which assumesthe form of an elongated centrally located bead or corrugation. Each ofthe ribs 82711 which form part of the heat dissipatingelements 825 isintegral with a sleeve 828b and is formed with three equidistantprojections in the form of beads or corrugations 850B which are parallelwith the projections 850A. The ribs 827a are integral with sleeves 8280to form the heat dissipating elements 826 and each thereof is providedwith five projections or beads 8500 which are parallel with theprojections 850A, 850B. The pipes 813-815 are of circular cross sectionand consist of identical material, preferably but not necessarily of thesame material as the heat dissipating elements 824-826. Thus, in theembodiment of FIG. 16, the boundary layer is influenced around each ofthe steam conductors so that the exchange of heat between streams of avaporous medium and the surrounding air currents is very satisfactoryimmediately in the area around the front conductor 813, 824.

In the condenser elements 707 and 807, all of the ribs 727a-727c and827a-827c are assumed to be equidistant from each other.

FIG. 17 illustrates a modified heat dissipating or heat transmittingelement 926 which may be utilized in the previously described condenserelements, for example, in the element 707 or 807, and which comprises asleeve 928a and a rib 9270, the latter having projections 950C in theform of ribs, beads or lugs provided at each of its sides to insure thatthe effect of the boundary layer is felt even less than if suchprojections were provided only at the one or the other side of the rib927c.

The various projections on the ribs 72712-7270, 827a- 8270 and 9270create turbulence around the respective heat dissipating elements, andsuch turbulence affects the boundary layer which latter forms some sortof an insulating coat or cushion around the heat dissipating elementsand tends to prevent direct contact of moving coolant with the materialof these elements.

The effect of the projections 750B-750C, 850A-850C and 950C upon theboundary layer may be explained by the theory that such projectionscause the aforementioned vibrations or burbulences and/or that theprojections provide additional edges which are in the path of the aircurrents so that the currents penetrate into and reduce the thickness ofor eliminate the insulating cushion or coat of fluid which forms theboundary layer.

It has been found that the projections of the type shown in FIGS. 13 to15 are very satisfactory in actual use and that such projections may beformed at very low cost. In addition, such projections do notundesirably affect the flow of air currents, i.e., they do not overlyincrease the resistance which the steam conductors offer to the flow ofcoolant in the direction of arrows X.

Finally, it should be mentioned that the results achieved with thecondenser elements or units of FIGS. 4-16 may be obtained by utilizingcondenser elements that embody a combination of features whichdistinguish the condenser elements 7, 107, 207, 307, 407, 507, 607, 707and 807 from each other. For example, it will be readily understood thateach of the condenser elements shown in FIGS. 4-12 may be provided withmeans which reduce the effect of or which eliminate the influence of theboundary layer; that the condenser elements of FIGS. 4-12 and 16 maycomprise steam conducting pipes of elliptical, oval or polygonalcross-sectional outline; that the groups of conductors shown in FIGS. 13to 15 may consist of different materials or that certain component parts(such as the heat dissipating elements or the pipes) of these conductorsmay consist of different materials; that the conductors of FIGS. 4 to 11and 13 to 16 may be staggered in the same way as or in a manner similarto that shown in FIG. 12; that the ribs may form integral parts of thesteam conducting pipes, i.e., that the sleeves of the heat dissipatingelements may be omitted; that the configuration of ribs in each group ofsteam conductors may be different; and many other modifications whichare too numerous to mention and which will readily occur to men skilledin the art upon perusal of the preceding disclosure. All that counts isto assemble the condenser elements in such a way that each thereofcomprises at, least two conductors one of which is located downsteam ofthe other thereof, as viewed in the direction in which air or anothercoolant flows and that the heat exchanging capacities of the conductorsare sufficiently different to insure that the temperature of condensatedischarged from their pipes is at least nearly the same.

1 also wish to mention that it is possible to provide a condenserelement or unit which embodies the features of the present invention andthe features of my aforementioned patent, for example, by providingmeans for regulating the rate of flow of a vaporous medium through thepipes, i.e., for varying the total' amounts of vaporous medium inconsecutive pipes as seen in the direction of the flow of coolant. inFIG. 11 which shows that the intake end of the pipe 514 may accommodatea removable annular throttling member 560 (shown in phantom lines) whichinsures that the rate of inflow of vaporous medium into the median pipe514 is less than the rate of inflow of vaporous medium into the frontpipe 513. The intake end of the rear pipe 515 accommodates anotherremovable throttling member 561 which reduces the rate of inflow ofvarious medium into this pipe to below the rate at which such medium mayflow into the median pipe 514. Thus, in addition to utilizing conductorsof different materials, the condenser element 507 may be constructed insuch a way that the rate of flow of vaporous media through differentgroups of its pipes is different, i.e., that the rate of flow diminishesin the direction of cool- This is illustrated schematically 17 ant flow.Identical. results can be obtained byutilizing pipes of differentdiameters.

Similar or otherwise constructed throttling means may be used in othercondenser elements, if desired. Such throttling means may also be usedfor uniformly reducing the rate of inflow of steam into each of thepipes in all of the: illustrated. condenser elements in the event thatthe temperature of coolant drops below such temperature at which thesteam condenser of my invention operates with optimum efficiency.However, whenever a condenser element is constructed in a manner tocombine two or more features of the present invention or one or morefeatures of the present invention and the feature disclosed in theaforementioned patent, care must be exercised that the heat exchangingcapacity of consecutive steam conductors preferably increases and thatthe total amounts of vaporous medium entering the consecutive conductorspreferably decrease at the same rate at which the temperature of coolantcoming in contact with the respective conductors increases (i.e.,proportionally with the drop in cooling capacity of the coolant) to makesure that the temperature of condensate at the discharge ends of all ofthe pipes is at least nearly the same.

The following specific example is being given merely for betterunderstanding of the invention and should not be construed in arestrictive sense:

It is assumed that the temperature of the air currents is. 20 C.- andthat the surface condenser of my invention comprises one or morecondenser units constructed in a manner as shown in FIGS. 4 and 5. Thetemperature of steam entering the header 18 is assumed to be 40 C.. Theair coming into contact with the heat dissipating elements 24 of thefront group of steam conductors 13, 24 is already heated to 15 C. at thetime it reaches the front group so that the total difference between thetemperature of steam entering the pipes 13 and the temperature ofsurrounding air is 55 C. The air currents reaching the second group ofsteam conductors 14, 25 are already heated to 6.5 C. so that the totaldifference between the temperature of steam entering the pipes 14 andthe temperature of air surrounding the heat dissipating elements 25 is46.5 C. At the time the air currents reach the third or rear group ofsteam conductors 15, 26 their temperature rises to 0.5 C, so that thetotal difference between the temperature of steam entering the pipes 15and the temperature of air brushing theheat dissipating elements 26 is40.5" C. Conse quently, the heat exchanging capacities of the conductors13, 24; 14, 25; 15, 26 must be proportioned as 40.5 246.5 :55, i.e., theratio of the heat exchanging capacity of a steam conductor 13, 24 to theheat exchanging capacity of a conductor 14, 25 must be inverselyproportional to the ratio of the differential between the temperature ofsteam entering a pipe 13 and the temperature of surrounding air and thedifferential between the temperature of steam entering the pipe 14 andthe temperature of surrounding air.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for vari ous applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic and specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a surface condenser, in combination, means for producing adirected current of coolant; a source of vaporous medium whosetemperature is higher than the temperature of coolant so that the mediumyields condensate in response to exchange of heat with the coolant; anda condenser unit including a pair of tubular conductors each having anintake end connected with said source and a condensate-dischargingsecond end, said conductors being disposed in the path of andsubstantially transversely to the direction of the flow of coolant sothat coolant brushing said conductors tends to form around saidconductors astagnant boundary layer which hinders the exchange of heatbetween the medium and the flowing coolant, one' of said conductorsbeing located upstream of the other conductor as seen in the directionof flow of the coolant so that coolant brushing said one conductor isheated and its cooling capacity decreases prior to brushing said otherconductor, said other conductor comprising means for reducing the effectof the boundary layer suflicien'tly to insure that the heat exchangingcapacity of said other conductor is superior to the heat'exchangingcapacity of said one conductor proportionally with the drop in coolingcapacity of the coolant whereby the temperature of condensate at bothsaid second ends is at least nearly the same.

2. A combination as set forth in claim 1, wherein the means for reducingthe effect of said boundary layer comprises external projections on saidother conductor.

3. A combination as set forth in claim 2, wherein each of saidconductors comprises an elongated pipe and radially arranged ribsprovided around the respective pipe, said projections forming part ofthe ribs on the pipe of said other conductor.

4. A combination as set forth in claim 3, wherein said projections arelugs disposed in planes substantially paral lel with the direction ofthe flow of coolant.

5. A combination as set forth in claim 3, wherein each of said ribs hasa first side and a second side and" wherein said projections areprovided along at least one side of each rib.

6. A combination as set forth in claim 1, wherein each of saidconductors comprises an elongated pipe and a plurality of heattransmitting elements surrounding. the

respective pipe, each of said heat transmitting elements comprising arib disposed in a plane substantially perpendicular to the axis of therespective pipe and the means for reducing the effect of the boundarylayer around said other conductor comprising a plurality of elongatedcor rugations provided on the ribs in the heat transmitting elements ofsaid other conductor, said corrugations being substantially parallelwith the direction of the flow of coolant.

7. In a surface condenser, in combination, means for producing adirected current of coolant; a source of vaporous medium whosetemperature is higher than the temperature of coolant so that the mediumyields condensate in response to exchange of heat with the coolant; anda condenser unit including a pair of tubular conductors each having anintake end connected with said source and a condensate-dischargingsecond end, said conductors being disposed in the path of andsubstantially transversely to the direction of the flow of coolant sothat coolant brushingsaid conductors tends to form around saidconductors a stagnant boundary layer which hinders the exchange of heatbetween the medium and the flowing coolant, one of said conductors beinglocated upstream of the other conductor as seen in the direction of flowof the coolant so that coolant brushing said one conductor is heated andits cooling capacity decreases prior to brushing said other conductor,each of said conductors comprising means for reducing the effect of' therespective boundary layer and the effect reducing means of said otherconductor being sufficiently superior to the effect reducing means ofsaid one conductor to insure that the heat exchanging capacity of saidother conductor is greater than the heat exchanging capacity of said oneconductor in proportion with the drop in cooling capacity of the coolantwhereby the temperature of condensate at both said second ends is atleast nearly the same.

8. In a surface condenser, in combination, means for producing adirected current of coolant; a source of vaporous medium whosetemperature is higher than the temperature of coolant so that the mediumyields condensate in response to exchange of heat with the coolant; anda condenser unit including a pair of tubular conductors each having anintake end connected with said source and a condensate-dischargingsecond end, said conductors being disposed in the path of andsubstantially transversely to the direction of the flow of coolant sothat coolant brushing said conductors tends to form around saidconductors a stagnant boundary layer which hinders the exchange of heatbetween the medium and the flowing coolant, one of said conductors beinglocated upstream of the other conductor as seen in the direction of flowof the coolant so that coolant brushing said one conductor is heated andits cooling capacity decreases prior to brushing said other conductor,said other conductor comprising means for reducing the effect of theboundary layer and the total area of its external surfaces being greaterthan the total area of external surfaces on said one conductor toinsure, in combination with a reduction in the effect of the boundarylayer, that the heat exchanging capacity of said other conductor issuperior to the heat exchanging capacity of said one conductorproportionally with the drop in cooling capacity of the coolant wherebythe temperature of condensate at both said second ends is at leastnearly the same.

9. In a surface condenser, in combination, means for producing adirected current of coolant; a source of vaporous medium whosetemperature is higher than the temperature of coolant so that the mediumyields condensate in response to exchange of heat with the coolant; anda condenser unit including a pair of tubular conductors each having anintake end connected with said source and a condensate-dischargingsecond end, said conductors being disposed in the path of andsubstantially transversely to the direction of the flow of coolant sothat coolant brushing said conductors tends to form around saidconductors a stagnant boundary layer which hinders the exchange of heatbetween the medium and the flowing coolant, one of said conductors beinglocated upstream of the other conductor as seen in the direction of flowof the coolant so that coolant brushing said one conductor is heated andits cooling capacity decreases prior to brushing said other conductor,said other conductor comprising means for reducing the effect of theboundary layer and the thermal conductivity of the material of saidother conductor being greater than the thermal conductivity of thematerial of said one conductor to insure, in combination with areduction in the effect of the boundary layer, that the heat exchangingcapacity of said other conductor is superior to the heat exchangingcapacity of said one conductor proportionally with the drop in coolingcapacity of the coolant whereby the temperature of condensate at bothsaid second ends is at least nearly the same.

10. In a surface condenser, in combination, means for producing adirected current of coolant; a source of vaporous medium whosetemperature is higher than the temperature of coolant so that the mediumyields condensate in response to exchange of heat with the coolant; anda condenser unit including a pair of tubular conductors each having anintake end connected with said source and a condensate-dischargingsecond end, said conductors being disposed in the pa'th'of andsubstantially transversely to the direction of the flow of' coolant sothat coolant brushing said conductors tends to form around saidconductors a stagnant boundary layer which hinders the exchange of heatbetween the medium and the flowing coolant, one of said conductors beinglocated upstream of the other conductor as seen'in the direction of flowof the coolant so that coolant brushing said one conductor is heated andits cooling capacity decreases prior to brushing said other conductor,said other conductor comprising means for reducing the effect of theboundary layer and the mass of said other conductor being different fromthe mass of said one conductor to insure, in combination with areduction in the effect of the boundary layer, that the heat exchangingcapacity of said other conductor is superior to the heat exchangingcapacity of said one conductor proportionally with the drop in coolingcapacity of the coolant whereby the temperature of condensate at bothsaid second ends is at least nearly the same.

11. In a surface condenser, in combination, means for producing adirected current of coolant; a source of vaporous medium whosetemperature is higher than the temperature of coolant so that the mediumyields condensate in response to'exchange of heat with the coolant; anda condenser unit including a pair of tubular conductors each having anintake end connected with said source and a condensate-dischargingsecond end, said conductors being disposed in the path of andsubstantially transversely to the direction of the flow of coolant sothat coolant brushing said conductors tends to form around saidconductors a stagnant boundary layer which hinders the exchange of heatbetween the medium and the flowing coolant, one of said conductors beinglocated upstream of the other conductor as seen in the direction of flowof the coolant so that coolant brushing said one conductor is heated andits cooling capacity decreases prior to brushing said other conductor,said other conductor comprising means for reducing the effect of theboundary layer and the total area of its external surfaces being greaterthan the total area of external surfaces on said one conductor and thethermal conductivity of its material being greater than the thermalconduc tivity of the material of said one conductor to insure, incombination with a reduction in the effect of the boundary layer andwith an increase in total area of external surfaces on the otherconductor, that the heat exchanging capacity of said other conductor issuperior to the heat exchanging capacity of said one conductorproportionally with the drop in cooling capacity of the coolant wherebythe temperature of condensate at both said second ends is at leastnearly the same.

References Cited by the Examiner UNITED STATES PATENTS 1,380,460 6/1921Bancel 146 1,524,520 1/1-925 Junkers 165146 1,911,522 5/1933 McIntyre165-146 1,974,876 9/1934 Schack l65146 2,107,478 2/1938 Happel 165146ROBERT A. OLEARY, Primary Examiner.

KENNETH W. SPRAGUE, CHARLES SUKALO,

Examiners.

1. IN A SURFACE CONDENSER, IN COMBINATION, MEANS FOR PRODUCING ADIRECTED CURRENT OF COOLANT; A SOURCE OF VAPOROUS MEDIUM WHOSETEMPERATURE IS HIGHER THAN THE TEMPERATRE OF COOLANT SO THAT THE MEDIUMYIELDS CONDENSATE IN RESPONSE TO EXCHANGE OF HEAT WITH THE COOLANT; ANDA CONDENSER UNIT INCLUDING A PAIR OF TUBULAR CONDUCTORS EACH HAVING ANINTAKE END CONNECTED WITH SAID SOURCE AND A CONDENSATE-DISCHARGINGSECOND END, SAID CONDUCTORS BEING DISPOSED IN THE PATH OF ANDSUBSTANTIALLY TRANSVERSELY TO THE DIRECTION OF THE FLOW OF COOLANT SOTHAT COOLANT BRUSHING SAID CONDUCTORS TENDS TO FORM AROUND SAIDCONDUCTORS A STAGNANT BOUNDARY LAYER WHICH HINDERS THE EXCHANGE OF HEATBETWEEN THE MEDIUM AND THE FLOWING COOLANT, ONE OF SAID CONDUCTORS BEINGLOCATED UPSTREAM OF THE OTHER CONDUCTOR AS SEEN IN THE DIRECTION OF FLOWOF THE COOLANT SO THAT COOLANT BRUSHING SAID ONE CONDUCTOR IS HEATED ANDITS COOLING CAPACITY DECREASES PRIOR TO BRUSHING SAID OTHER CONDUCTOR,SAID OTHER CONDUCTOR COMPRISING MEANS FOR REDUCING THE EFFECT OF THEBOUNDARY LAYER SUFFICIENTLY TO INSURE THAT THE HEAT EXCHANGING CAPACITYOF SAID OTHER CONDUCTOR IS SUPERIOR TO THE HEAT EXCHANGING CAPACITY OFSAID ONE CONDUCTOR PROPORTIONALLY WITH THE DROP IN COOLING CAPACITY OFTHE COOLANT WHEREBY THE TEMPERATURE OF CONDENSATE AT BOTH SAID SECONDENDS IS AT LEAST NEARLY THE SAME.